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leader1201 02-24-2013 11:29 PM

Need help on executing chroot command
 
Hi all,

I am trying to execute chroot command by changing the root in ubuntu machine.

Let me explain the situation.
I was mounted an ubuntu image in /mnt/ubuntu directory using follwoing command :
mount /dev/mapper/loop1p1 /mnt/ubuntu
it was successfully executed. so finally i want to install new package in the ubuntu image which is ther /mnt/ubuntu . In order to execute the chroot command i was setting chroot environment by following commands:

mount -o bind /dev /mnt/ubuntu/dev
mount -o bind /proc /mnt/ubuntu/proc
mount -o bind /sys /mnt/ubuntu/sys


The above commands also executing successfully.
finally i am trying to install linux-image kernel package on mounted image which is there in /mnt/ubuntu.

chroot /mnt/ubuntu dpkg -i tmp/linux-image.deb
chroot: failed to run command `dpkg': No such file or directory

this is the error i am getting .
please help me.

regards,
Prasad.

psionl0 02-24-2013 11:34 PM

I think you would have to mount -o bind whatever directory dpkg is in.

T3slider 02-24-2013 11:35 PM

Try passing the location of dpkg explicitly. Otherwise, try chrooting into it and executing the command manually so you can see what's happening.
Code:

# chroot /mnt/ubuntu
# /usr/bin/dpkg -i /tmp/linux-image.deb


leader1201 02-24-2013 11:59 PM

Hi T3slider,

I have tried both the cases which you mentioned in the comments.

chroot /mnt/ubuntu /usr/bin/dpkg /tmp/linux-image.deb
chroot: failed to run command `/usr/bin/dpkg': No such file or directory

second option :
first i have this command . this command it self showing error.
chroot /mnt/ubuntu
chroot: failed to run command `/bin/bash': No such file or directory

regards,
prasad.

T3slider 02-25-2013 05:31 PM

I think you need to have a look in /mnt/ubuntu when it's mounted -- it seems it does not contain files necessary for chrooting (or booting). Either some important directory is not being mounted, or you do not have a complete Ubuntu install on /dev/mapper/loop1p1.

leader1201 02-25-2013 09:28 PM

Today i will change the ubuntu image and try again.

leader1201 02-26-2013 07:20 AM

chroot /mnt/ubuntu it self fails
 
hi ,

i am unable to execute the chroot /mnt/ubuntu command this command showing following error.

chroot: failed to run command `/bin/bash': No such file or directory

please help me.

regards,
Prasad.

TobiSGD 02-26-2013 07:29 AM

As said before, check the directory for existance of /bin/bash, it seems that you don't have a fully functional install in that image.

leader1201 02-26-2013 07:42 AM

first i have taken one ubuntu image which is ubuntu-flat.vmdk .
this i have converted into raw format using qemu converter

qemu-img convert ubuntu-flat.vmdk -O raw ubuntu-flat.raw

i find out the free loop device . suppose i have taken loop5 in /dev/loop5 location.

losetup /dev/loop5 ubuntu-flat.raw.
kpartx -a /dev/loop5
mkdir /mnt/ubuntu
mount /dev/mapper/loop5p1 /mnt/ubuntu
mount -o bind /dev /mnt/ubuntu/dev (for this befor i have created dev directory in the /mnt/ubuntu location manually)
mount -o bind /proc /mnt/ubuntu/proc(proc also created before executing)
mount -o bind /sys /mnt/ubuntu/sys(sys also created before executing)

next i am trying to execute
chroot /mnt/ubuntu dpkg -i /tmp/somepackage.deb

Problems coming now as i mentioned above.

so is there any wrong procedure i am following .

regards,
prasad

TobiSGD 02-26-2013 09:34 AM

After you mount the Ubuntu image, just check, using ls, if /bin/bash is present in the image:
Code:

ls -l /mnt/ubuntu/bin/bash

leader1201 02-26-2013 11:03 PM

its not there in that image.

ls /mnt/server/bin/bash
ls: cannot access /mnt/server/bin/bash: No such file or directory

TobiSGD 02-26-2013 11:31 PM

Then the image is most likely not a complete system image and chrooting into it won't work.

leader1201 03-04-2013 12:32 AM

yes, My image gets corrupted and i have taken new image.I followed same procedure as i written in previous.
This time i am able to perform chroot command.


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